1. Field of the Invention
The present invention relates to a key-to-be-depressed designating apparatus which is suitable when being used for the performance practice of a keyboard-type electronic musical instrument and the like.
2. Prior Art
In one conventional key-to-be-depressed designating apparatus, the performer can practice the performance by depressing keys which are sequentially designated by the small lamps (e.g., LEDs) sequentially lighted on in accordance with the progress of a tune to be performed. However, when the performer does not depress the designated key, the conventional apparatus immediately stops the light-on operation of the lamps at that key-depression timing and waits for the correct key-depression to be made by the performer.
Such kind of key-to-be-depressed designating techniques are specifically described in Japanese Patent Laid-Open Publication No. 2-189572, entitled "Automatic Key-Depression Designating Apparatus".
To beginners, even if the performance practice is made by use of the keyboard-type electronic musical instrument having the key-to-be-depressed designating apparatus, errors caused by the mis-touch (i.e., key-touch event in which wrong keys are depressed by mistake) or delay of key-depression should occur frequently.
In the conventional key-to-be-depressed designating apparatus, every time the mis-touch or delay of key-depression occurs, light-on operation of the key-to-be-depressed designating lamps is stopped, which avoids the smooth progress of the tune to be performed.
In addition, the above-mentioned drawback sometimes affects the performance practice.